The prevalence of systemic sclerosis in the U.S. is estimated to be approximately 68,000, based on a recent epidemiology study published in 1997 which reports a prevalence of 240 cases per million. Systemic sclerosis is three to four times more common in women than in men. Based on the prevalence, systemic sclerosis is an orphan disease and Connetics Corporation has obtained an orphan drug designated for recombinant human relaxin. A non-controlled study conducted in the 1950's using purified porcine relaxin for the treatment of 23 subjects with scleroderma reported some efficacy, particularly in raged to healing of digital ulcers and Raynaud's phenomenon. The ability of ralxin to be evaluated critically for its beneficial effects in this disease was limited by uncertainties concerning the purity of the relaxin preparation sold at this time. The clinical features of scleroderma reflect variable contributions of the pathologic processes of vascular injury, tissue inflammation, secondary fibrosis and ultimately tissue atrophy. Accordingly, this study (RLXN.C.005) employs a variety of assessment techniques and measures which are relevant to judging the clinical status of individuals with systemic sclerosis but which are also reflective of diverse pathologic processes operative in this disorder. These techniques and measures are basis of the experimental design in this trial. The well-defined biologic properties of relaxin would suggest the potential for primary effects on measures of the tissue fibrosis and vascular status and secondarily on tissue atrophy. The study design will be a multicenter, randomized, double-blind, placebo controlled trial. A minimum of 180 and a maximum of 200 subjects diagnosed with systemic sclerosis with diffuse scleroderma will be randomized to six months of continuous subcutaneous infusion treatment to one of three parallel treatment groups in a 2:2:1 ratio, with a minimum of 72 subjects in each in the 25 microgram/kg/day and placebo groups, and 36 subjects in the 10 micrograms/kg/day group. The Boston University School of Medicine / Boston Medical Center is to recruit 20-30 subjects for this study.